The Department of Defense admitted that 51 labs in 17 states and three different countries received suspected live samples of anthrax over the course of a one-year period, and added that the number of recipients may rise as the investigation continues.

On May 22, the US Centers for Disease Control and Prevention (CDC) notified the Pentagon that one of the private lab partners had detected the growth on live anthrax on a sample that was “supposedly inactivated…we felt that it was [an] inactivate and safe shipment,”Deputy Secretary of Defense Robert O. Work said at a briefing on Wednesday.

“But it turned out not to be the case,” he added.

The Department of Defense said that the probe has not found any indication that the samples were sent as a result of a deliberate action or that anyone had been infected by the lethal bacteria. The agency also said there was no danger to the public from the anthrax.

The Pentagon previously said that the anthrax had “accidentally” been sent to 24 laboratories in 11 states and two foreign countries. The agency later disclosed that the three countries that received the live spores were Australia, South Korea and Canada. In the US, a lab in the District of Columbia also received a shipment of the anthrax, on top of those in the 17 states.

“The department has regularly shipped inactivate ‒ or ‘killed’ ‒ biological material to other federal and private partner labs for development of biological countermeasures,” Work said.

“So, for example, if we wanted to have a field detector kit that would tell us that anthrax was in the area, what we do is we work with labs and we work with partners who we then provide these killed spores with so that they would then be able to develop a detector that would help our men and women if they encounter such an organism on the battlefield,” he added.

As a precaution, the DoD has asked labs to stop working on those samples until further notice from the Pentagon and the CDC. The government is also in the midst of testing every previously inactivated anthrax sample ‒ 400 lots worth ‒ to ensure that it does not contain any live spores.

Navy Cdr. Franca Jones, director of medical programs for chemical and biological defense, said it takes 10 days in each case to define if anthrax samples received by labs are live or dead ones.

Under Secretary of Defense for Acquisition, Technology and Logistics Frank Kendall is leading the review into all DoD laboratory procedures and protocols for killing live anthrax spores. Kendall will submit his preliminary findings to Work and Secretary of Defense Ashton Carter within 30 days.

Kendall is charged with discovering the root cause of the incomplete deactivation of the samples, why the live spores were not caught during sterility testing, and identifying any systemic problems that caused the inadvertent shipments to occur. His review is separate from the CDC’s probe into DoD labs, Work said.

“I’m assembling a team of experts from the government and private sector to examine the inactivation processes. They will report preliminary findings and recommendations by the end of June,” Kendall said. “The final report depends upon the completion of the CDC’s investigation.”

The Pentagon promised to update the number of labs that received the live samples on a daily basis, as the investigation continues.